Particularly, a heating means that is in charge of heating an inner portion of the vehicle is configured so that a heat exchange medium for lowering a temperature of an engine heats external air while being circulated in a heater core, thereby heating the inner portion of the vehicle.
However, a diesel engine among engines has high heat exchange efficiency, such that it requires a longer time in heating the heat exchange medium cooling the engine as compared with a gasoline engine at the time of an initial start-up of the vehicle.
Therefore, in the winter, in a vehicle including the diesel engine, the heating of the heat exchange medium after the initial start-up becomes late, such that initial indoor heating performance is deteriorated.
In order to solve the problem as described above, a vehicle air heating type heater having a form in which air blown toward an inner portion of the vehicle is directly heated using various means has been suggested.
The air heating type heater directly heats the air to further improve heating performance. However, a space corresponding to a size of the air heating type heater is occupied in a situation in which it is difficult to secure a sufficient space in the engine room in accordance with the trend toward miniaturization and efficiency improvement, thereby making it possible to hinder the miniaturization.
Particularly, in the case of a cartridge heater using a nichrome wire, it is difficult to control a temperature, there is a risk that the cartridge heater will be overheated when the air is not blown toward the cartridge heater, an insulation problem due to a high voltage may occur, and there is a risk of a fire.
In addition, a vehicle air conditioning apparatus using a positive temperature coefficient (PTC) heater has been suggested in Japanese Patent Laid-Open Publication No. 2009-255739, and the PTC heater according to the related art is shown in FIG. 1.
In FIG. 1, an air flow direction is denoted by an arrow, and the PTC heater shown in FIG. 1 is configured to include heat source parts 11 formed of a PTC element, heat radiating parts 12 contacting the heat source parts 11 to effectively radiate heat, and a housing 20 enclosing and protecting terminal parts, the heat source parts 11, and the heat radiating parts 12.
Although the PTC heater according to the related art may have a partial difference in a detailed structure, the heat source parts are formed in parallel with the air flow direction, such that a formation area of the heat source parts has a direct influence on heat generation performance. Therefore, there is a limitation in decreasing a thickness (air flow direction) of the PTC heater.
Particularly, in the PTC heater, since an electrical problem may occur in the case in which a heat radiating condition is not good, the heat radiating parts (generally, heat radiating fins) should be formed. Therefore, a process of manufacturing and assembling the heat radiating parts is complicated, and entire durability of the PTC heater may be deteriorated in the case in which heat radiation is not effectively performed.
An example of a vehicle air conditioning apparatus using a PTC heater is shown in FIG. 2.
The vehicle air conditioning apparatus shown in FIG. 2 is configured to include an air conditioning case 30 provided with a floor vent 31, a defrost vent 32, and a face vent 33 of which opening degrees are adjusted by the respective doors 31d, 32d, and 33d; an evaporator 41 disposed in the air conditioning case 30 and cooling air; a heater core 42 having a high temperature coolant flowing therein to heat the air; and the PTC heater 43 disposed behind the heater core 42 in an air flow direction.
Here, the PTC heater is disposed so as to maintain a predetermined interval from the heater core. Therefore, an inner space of the air conditioning case is occupied by an amount corresponding to the predetermined interval, thereby making it possible to deteriorate space efficiency.
In addition, in order to prevent a pressure drop of the air and decrease a cost, the PTC heater is mainly positioned at a central region of the heater core in a height direction. Therefore, air passing through upper and lower regions in which the PTC heater is not positioned is moved in a state in which it is not appropriately heated, such that heating performance cannot but be deteriorated.
(A flow of the air moved in a state in which the air is not appropriately heated is denoted by a dotted arrow).
Therefore, development of a heater capable of improving heating performance by improving heat exchange performance in spite of being directly heat-exchanged with air, being miniaturized, being easily controlled, and increasing safety by preventing a problem due to overheating has been demanded.